Convicted thief and failed hot-tub salesman Chad Milligan admired Donald Trump so much that he tried to change his name to Donald Trump Jr. in 2000, but the Manhattan mogul sued him. The Oregon man and The Donald eventually settled on allowing Milligan to legally change his name to Sir William Trump Jr.

Now Trump Jr. is backing his idol to the hilt in the presidential election, although he has some criticism of the candidate.

“He should have started a lot earlier attacking Hillary,’’ the 45-year-old Junior told The Post. “I hope he wins, but it doesn’t look good.”

Trump Jr. said he has a Trump/Pence sign on his Medford lawn and will be one of the first people in Oregon to cast a vote for The Donald on Tuesday.

‘If he wins, there will be a man as president who gave me my name.’

“If he wins, there will be a man as president who gave me my name,” Trump Jr. said, adding he might write a book about his experiences.

But he admitted that since changing his name, things haven’t always gone smoothly.

“It’s been rough carrying his name. Everybody thinks I have a lot of money,” Trump Jr. said. “A girl I know just asked me for $3 million.”

He said he wasn’t surprised when Trump decided to run for the Oval Office.

“I am a fan, and I always expected him to pull something like this,” Junior said. “He loves to . . . be seen. Running for president, maybe he spent $2 billion, but that’s cheap because look at all the free media he got. How much more can you turn on the TV and see Trump?”